Currently, the existing touch screen detecting manners comprise: resistance type touch detecting manner, capacitance type touch detecting manner, infrared touch detecting manner, sound surface wave touch detecting manner, electromagnetic touch detecting manner and so on. The touch screens in mobile devices such as a mobile phone, a tablet PC, etc. commonly use the resistance type and the capacitance type technologies. In the resistance type technology, the touch panel is covered with two layers of Indium Tin oxide (ITO). When the touch panel using the resistance type technology is touched, the two ITO layers make contact with each other, so that a switch corresponding to the touch position is turned on, and corresponding information is transferred to the processor for further processing. In the capacitance type technology, the touch panel is covered with a material which can store charge. Upon the touch panel using the capacitance type technology being touched, a small amount of charges are attracted to the touch point, and the circuit in the touch panel measures the charges attracted to the touch point, and transfers the corresponding information to the processor for processing.
The above touch screen technologies both use a line sequence scanning manner to detect touch, store a change of the touch sensor (that is, the touch panel) into the processor, and the processor converts the change of the touch sensor into a corresponding coordinate on the display screen, and the system performs user's operation according to the position of the corresponding coordinate.
FIG. 1 is a block view of a capacitance type touch screen system. FIG. 2 is a simplified schematic view of a mutual capacitance circuit. The mutual capacitance circuit comprises a sensing line 111, a driving line 112, and a capacitance coupling node 113 (that is, detecting unit C0), wherein the sensing line 111 and the driving line 112 are separated spatially. The driving line 112 is connected between the voltage source 120 and the capacitance coupling node 113, to transfer driving signal to the capacitance coupling node 113. The sensing line 111 is connected between the capacitance coupling node 113 and the capacitance detecting circuit 130, to transfer the detecting signal of the capacitance coupling node 113 to the capacitance detecting circuit 130. 114 and 115 are parasitic capacitance generated between the coating layers of the touch panel.
The touch detecting process will be described below by taking the capacitance coupling node 113 as an example.
Upon the capacitance coupling node 113 being not touched, the charges on the capacitance coupling node 113 remain constant. Upon the capacitance coupling node 113 being touched, the charges carried by the detecting unit C0 changes, and at this time, the detecting signal that the charges have changed is transferred to the capacitance detecting circuit 130 by the sensing line. The capacitance detecting circuit records the position information of the capacitance coupling node 113 where charges have changed, and sends the recording result to the processor, to make the processor perform corresponding operation.
FIG. 3 is a schematic view of a detecting method of a conventional touch screen, in which touch scanning is performed sequentially on each pixel point in each row, and the processor detects and records the scanning result. With respect to a touch screen with a resolution of M×N (that is, in the touch screen, the total row number of pixel points is N, and the total column number is M, wherein M and N are positive integers), if the touch screen detecting is performed by using the conventional touch screen detecting method, it totally needs to perform M×N times of detecting.
FIG. 4 is a schematic view of the driving signal which is input to the capacitance coupling node in each row through driving lines by the voltage source 120 when using the method corresponding to FIG. 3. When a first period arrives, the driving signal is input to the first row, to make the detecting circuit sequentially performing detecting on pixel points (that is, the capacitance coupling nodes) in the first row. When a second period arrives, the driving signal is input to the capacitance coupling nodes in the second row, to make the detecting circuit sequentially performing detecting on the capacitance coupling nodes in the second row. In the same way, when the nth period arrives, it performs detecting on the capacitance coupling nodes in the nth row, wherein N is the number of the rows of the touch screen.
It can be seen from the above analysis that as the resolution of the touch screen increases, the detecting times of the processor increase by several times, and the requirement on the calculating speed of the processor is higher, and once the calculating speed of the processor cannot be improved to a corresponding level in a short period, the apparatus would occur the cases of responding slowly, halting, or not responding (for example, system halted).